Question

Distinguish between conductor and semiconductor on the basis of band theory of solids.

Answer 1

Metals are good conductors of electricity. Insulators are bad conductors of electricity. Similarly, semiconductor devices are partial conductors of electricity means their conductivity lies between conductors and insulators.

In case of conductor, electrons fill the conduction band partially. The overlapping of both the bands i.e. valence and conduction band also take place. This shows that no forbidden energy gap is present.

In case of semiconductors the conduction band is empty and the valence band is fully filled with electrons. Like insulators, forbidden energy gap is not so large in case of semi conductors. The energy gap is very small.